JP3339380B2 - Manufacturing method of multilayer ceramic electronic component - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer ceramic electronic component, and more particularly to a method for forming an internal conductor by a conductive paste and absorbing a step due to the thickness of the internal conductor. And a step of stacking such ceramic green sheets on which a step-absorbing ceramic film containing the above ceramic material is formed.

[0002]

2. Description of the Related Art Generally, when manufacturing a multilayer ceramic electronic component, a plurality of ceramic green sheets are prepared, and these ceramic green sheets are stacked. On a main surface of a specific one of the stacked ceramic green sheets, an internal conductor for forming a coil, a capacitor, a varistor, an LC filter, or the like is provided according to a function of a multilayer ceramic electronic component to be obtained, for example, a screen. The conductive paste is formed in a desired pattern using a printing method.

For example, when manufacturing a laminated chip coil, through holes are provided in a specific ceramic green sheet, and when a plurality of ceramic green sheets are stacked, a line is formed on the main surface of each different ceramic green sheet. The plurality of inner conductors formed to extend in a spiral shape are spirally extended by through-hole connection.

Next, the above-mentioned ceramic green sheets are stacked and pressed to form a laminate,
This is cut into chip sizes and then fired. Then, external terminal electrodes are formed on both ends of each chip so as to be electrically connected to each end of the above-described spirally extending internal conductor, thereby completing a desired laminated chip coil.

With the miniaturization of such laminated chip coils, the internal conductors are becoming finer, and the thickness of the internal conductors is also increasing in order to improve the characteristics. Therefore, the inner conductor is usually printed with a thickness of 10 to 20 μm, but may be printed with a thickness of, for example, 20 μm or more. When the internal conductor made of the conductive paste is formed with a thickness of 20 μm or more, a relatively large step occurs due to the thickness of the internal conductor on the ceramic green sheet, and therefore, in a pressing process after stacking the ceramic green sheets. In some cases, the inner conductor is greatly deformed.

In order to prevent such undesired deformation of the internal conductor, a step due to the thickness of the internal conductor is formed in a region where the internal conductor is not formed on the main surface of the ceramic green sheet on which the internal conductor is formed. A step-absorbing ceramic film containing a raw ceramic material of substantially the same material system as the ceramic green sheet is formed by, for example, screen printing so as to absorb the ceramic green sheet.

[0007]

FIG. 6 is an enlarged sectional view showing a state in which the inner conductor 2 is printed on the main surface of the ceramic green sheet 1 by using a conductive paste and dried. As shown in FIG.
When formed with a thickness of not less than m, the cross section of the internal conductor 2 tends to be substantially semi-circular or semi-elliptical due to the surface tension of the conductive paste and the like, and tends to swell.
This tendency becomes more prominent as the thickness of the internal conductor 2 increases.

FIG. 7 is an enlarged sectional view showing the step of forming the step absorption ceramic film 3. In this step, a raw ceramic material 4 having substantially the same material system as the ceramic green sheet 1 is applied to a squeegee 7 on a screen 6 having a negative pattern 5 with respect to the inner conductor 2 so that the ceramic green sheet 1 is screen-printed in a predetermined pattern.

However, as described above, if the cross section of the internal conductor 2 has a substantially semi-circular or semi-elliptical shape and is raised, the screen 6 is difficult to adhere to the internal conductor 2, so that the screen 6 is undesirably undesired. The ceramic material 4 is likely to wrap around the lower surface side of 6. From this, FIG.
As shown in FIG. 7, the step absorption ceramic film 3 may be in a state of forming an overcoat portion 8 covering a part of the internal conductor 2. Such an overcoat portion 8 hinders proper connection between the internal conductor 2 and an adjacent internal conductor (not shown) in a laminated state, and causes a decrease in the yield rate of the obtained laminated chip coil. .

Further, it becomes difficult to control the thickness of the step absorption ceramic film 3. In addition, since the remaining portion 9 of the ceramic material 4 attached to the lower surface of the screen 6 must be removed by the next screen printing step, the screen printing step may be continuously performed for this removing step. Can not. The width of the inner conductor 2 is, for example, 120 μm.
When the width is not less than m, a flat surface is easily formed at the center in the width direction, so that the cross-sectional shape does not become relatively semicircular or semi-elliptical and does not swell. It is easy to adhere to the conductor 2 and the above-mentioned problem hardly occurs. Therefore, these problems are caused by the fact that the width of the internal conductor 2 is 12
When it is less than 0 μm, it is particularly easy to occur.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a multilayer ceramic electronic component, which is improved so that a ceramic film for absorbing a step can be favorably formed.

[0012]

According to the present invention, a plurality of ceramic green sheets are prepared, and an inner conductor is formed of a conductive paste on a main surface of a specific one of the plurality of ceramic green sheets. On the main surface of the ceramic green sheet on which the conductor is formed, in a region where the internal conductor is not formed, a raw ceramic of substantially the same material system as the ceramic green sheet is used so as to absorb a step due to the thickness of the internal conductor. Forming a step-absorbing ceramic film containing a material, and then stacking and pressing a plurality of ceramic green sheets, each of which is directed to a method of manufacturing a multilayer ceramic electronic component, the above-described technical problem. Before forming the step absorption ceramic film, the inner conductor is flattened, It is characterized in that it comprises further the step of pre-pressing a ceramic green sheet.

In the step of forming the internal conductor,
The present invention is more advantageously applied when the internal conductor is formed on a ceramic green sheet with a cross-sectional dimension of less than 120 μm in width and 20 μm or more in thickness. A method for manufacturing such a laminated chip coil, wherein a specific ceramic green sheet is provided with a through hole and a plurality of inner conductors are formed to extend spirally through the through hole. In this, the present invention is applied more advantageously.

Further, when the step absorbing ceramic film is formed by screen printing, the present invention is more advantageously applied.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Although the present invention is applicable to multilayer ceramic electronic components in general, the embodiments of the present invention will be described below with reference to a method of manufacturing a multilayer chip coil. FIG. 3 is a perspective view showing the appearance of the laminated chip coil 11 obtained by the manufacturing method according to the embodiment of the present invention. The laminated chip coil 11 is a laminated chip 1
2, and external terminal electrodes 13 and 14 formed on both ends of the multilayer chip 12.

In order to obtain the laminated chip 12, a plurality of ceramic green sheets including ceramic green sheets 15, 16, 17 and 18 as shown in FIG. 4 are prepared. In FIG. 4, the ceramic green sheets 15 to 18 are illustrated to have a dimension that gives one laminated chip 12, but in the case of factory-scale production, a so-called mother state, that is, a plurality of A ceramic green sheet having a size capable of taking out the multilayer chip is prepared, and cut after completing a stacking and pressing step described later to obtain a plurality of multilayer chips.

The ceramic green sheets 15 to 18 are
For example, it has a thickness of 40 μm. The ceramic green sheets 15 to 17 are provided with through holes 19, 20 and 21, respectively. Next, linearly extending internal conductors 22, 23, 24, and 25 are formed on the main surfaces of the ceramic green sheets 15 to 18, respectively, by a conductive paste. The above-described through holes 19, 20 and 21 respectively correspond to the inner conductor 2
2, 23 and 24 at each end, thus
In FIG. 4, through-holes 19 to 21 are indicated by alternate long and short dash lines.
As shown in FIG.
A conductive path extending spirally through the through holes 19 to 21 is formed.

The internal conductor 22 has a lead conductor 26 extending along one edge of the ceramic green sheet 15, and the internal conductor 25 extends along the other edge of the ceramic green sheet 18. It has a lead conductor 27. These lead conductors 26 and 27 constitute each end of a spiral conductive path formed by the internal conductors 22 to 25.

The internal conductors 22 to 25 are formed by, for example, screen printing. Inner conductors 22-2
5 has a cross-sectional dimension of less than 120 μm in width and 20 μm or more in thickness, for example, 80 μm in width and 30 μm in thickness. The internal conductor 22 having such a sectional dimension
When 25 to 25 are formed, as described above with reference to FIG. 6, due to the surface tension of the conductive paste and the like, each cross section of the internal conductors 22 to 25 becomes substantially semicircular or semielliptical. Tend to get excited.

In this embodiment, the inner conductors 22 to
After the ceramic green sheets 15 to 18 on which the inner conductors 25 are formed are dried, the ceramic green sheets 15 to 18 on which the inner conductors 22 to 25 are formed are pre-pressed in order to flatten the inner conductors 22 to 25. It is. FIG. 1 is an enlarged cross-sectional view typically showing a process for pre-pressing the ceramic green sheet 15 on which the internal conductor 22 is formed. In such a pre-pressing step, for example, a pressing body 2 such as a drum roll
8 acts on the ceramic green sheet 15,
The internal conductor 22 is flattened. At this time, the inner conductor 22 is compressed so that its upper surface becomes flat. Although not shown in FIG. 1, a part of the internal conductor 22 in the thickness direction may be buried in the ceramic green sheet 15 by the preliminary pressing.

In the above pre-pressing, in order to obtain a sufficient pressing effect while preventing undesired elongation and breakage of the ceramic green sheet 15, it is preferable to apply a pressure of 50 to 150 kgf / cm ^{2 and} a pressure of 25 to 150 kgf / cm ^2.
A temperature of ６０60 ° C. is provided. It is also important to select pressing conditions that do not substantially change the width of the internal conductor 22.

A similar pre-pressing step is performed by
Ceramic green sheet 1 on which each of 25 is formed
6 to 18 are also performed. Next, the internal conductors 22 to
Ceramic green sheet 1 on which each of 25 is formed
In each of the main surfaces 5 to 18, the ceramic green sheets 15 to 15 are formed in a region where the internal conductors 22 to 25 are not formed so as to absorb a step due to the thickness of the internal conductors 22 to 25.
Step-absorbing ceramic films 29, 30, 31 and 32 containing a raw ceramic material of substantially the same material system as 18 are formed, for example, by screen printing, respectively.

FIG. 5 shows the step absorbing ceramic film 29 separated from the ceramic green sheet 15 on which the internal conductor 22 is formed, so that the shape of the step absorbing ceramic film 29 can be easily understood. FIG. 2 is an enlarged cross-sectional view typically showing a step of forming the step absorption ceramic film 29. This step proceeds similarly to the step shown in FIG. That is, a raw ceramic material 33 of substantially the same material system as the ceramic green sheet 15 is caused to act on the screen 35 having the negative pattern 34 on the inner conductor 22 by causing a squeegee 36 to act on the ceramic green sheet 15. Is screen-printed with a predetermined pattern, whereby the step absorption ceramic film 29 is formed.

At this time, since the internal conductor 22 has been flattened in advance, the screen 35 is easily brought into close contact with the internal conductor 22, so that the ceramic material 33 does not wrap around the lower surface of the screen 35. Therefore, it is possible to prevent the formation of the overcoat portion 8 as shown in FIG. 7 described above, and it is possible to improve the accuracy of the printing position of the step absorption ceramic film 29. Further, the thickness of the step absorption ceramic film 29 can be easily controlled. A ceramic material 3 is provided on the lower surface of the screen 35.
Since 3 does not remain undesirably, the step of removing it does not hinder the continuous execution of the screen printing step.

Similarly, the step absorbing ceramic films 30 to 3
2 is also performed on the ceramic green sheets 16 to 18 on which the internal conductors 23 to 25 are respectively formed. Next, the ceramic green sheet 15 ~
18 are stacked and pressed. In this press step, for example, a rigid press is applied. In order to further increase the inductance of the laminated chip coil 11 to be obtained, for example, the stacking of ceramic green sheets having the same form as the ceramic green sheets 16 and 17 shown in FIG. 4 may be further repeated. Further, in order to prevent the internal conductor 22 from being exposed to the outside, a ceramic green sheet having no internal conductor or the like may be stacked on the ceramic green sheet 15.

Next, the ceramic green sheets 15-1
The laminated body composed of a plurality of ceramic green sheets including No. 8 is cut into a chip size as necessary, to be a raw laminated chip, and then fired. In this way, the laminated chip 12 shown in FIG. 3 is obtained. When the external terminal electrodes 13 and 14 are formed at both ends of the laminated chip 12, these external terminal electrodes 13 and 14 are formed.
Are the lead conductors 2 exposed on each end face of the multilayer chip 12.
6 and 27, respectively, and the desired laminated chip coil 11 is completed.

Although the present invention has been described with reference to the illustrated method of manufacturing the laminated chip coil 11, the present invention
The manufacturing method of the multilayer chip coil of another embodiment is further applied to, for example, a multilayer ceramic capacitor, a multilayer ceramic varistor, a multilayer ceramic L other than the multilayer chip coil.
The present invention is equally applicable to a method for manufacturing a multilayer ceramic electronic component such as a C filter.

The step absorbing ceramic films 29 to 32
Is formed by screen printing in the above-described embodiment, but may be formed by another printing method.

[0029]

As described above, according to the present invention, after the inner conductor is formed on the main surface of the ceramic green sheet by the conductive paste, the inner conductor is planarized.
After pre-pressing the ceramic green sheet on which the internal conductor is formed, a raw ceramic of substantially the same material system as the ceramic green sheet is formed in a region where the internal conductor is not formed so as to absorb a step due to the thickness of the internal conductor. A step-absorbing ceramic film containing a material is formed. Therefore, the step absorbing ceramic film can be more easily formed in an appropriate region, and the inner conductor can be prevented from being undesirably covered with the ceramic material for the step absorbing ceramic film. The non-defective rate of electronic components can be increased.

Further, since the pre-press also contributes to increasing the density of the internal conductors and the ceramic green sheets, it is necessary to make the internal conductors and the ceramic green sheets less likely to flow in a pressing step after stacking a plurality of ceramic green sheets. Therefore, undesired deformation of the inner conductor can be suppressed. This also
This can contribute to an improvement in the yield rate of the obtained multilayer ceramic electronic component. In addition, the number of layers in the multilayer ceramic electronic component can be increased without any problem, and as a result, the performance of the multilayer ceramic electronic component can be improved.

In the step of forming an internal conductor included in the method for manufacturing a multilayer ceramic electronic component according to the present invention,
When the internal conductor is formed on a ceramic green sheet with a cross-sectional dimension of less than 120 μm in width and 20 μm or more in thickness, the internal conductor is likely to have a cross-sectional shape that rises in a semicircular or semi-elliptical shape. There is a more important significance in pre-planarizing.

Further, in order to manufacture such a laminated chip coil, a through hole is provided in a specific ceramic green sheet, and a plurality of internal conductors are formed to extend spirally through the through hole. In this method, when the present invention is applied, it is possible to appropriately cope with the miniaturization of the internal conductor accompanying the miniaturization of the multilayer chip coil, and also appropriately cope with the thickening of the internal conductor for improving the characteristics. can do. Further, in the case of the laminated chip coil having such a structure, if the step absorption ceramic film is formed so as to undesirably cover the internal conductor, it is highly likely that the through hole connection is obstructed, resulting in a serious defect. However, when the step absorbing ceramic film is formed in an appropriate region according to the present invention, through-hole connection is ensured, and the yield of the laminated chip coil can be increased. Further, as described above, since the number of layers can be increased without any problem, a high inductance value can be obtained by increasing the number of layers.

When the step-absorbing ceramic film is formed by screen printing, the inner conductor is planarized in advance according to the present invention, so that the screen easily adheres to the inner conductor. The raw ceramic material for forming the step absorption ceramic film does not wrap around. Therefore,
It is possible to prevent the ceramic material from being applied so as to cover the internal conductor, and it is possible to improve the accuracy of the printing position of the step absorption ceramic film. Further, the thickness of the step absorption ceramic film can be easily controlled. Further, since the raw ceramic material does not undesirably remain on the lower surface side of the screen, the step of removing the raw ceramic material does not hinder the continuous execution of the screen printing step.

[Brief description of the drawings]

FIG. 1 is a characteristic step included in a method for manufacturing a laminated chip coil according to an embodiment of the present invention, which is an internal conductor 22;
It is an expanded sectional view which shows the preliminary press process of the ceramic green sheet 15 for flattening.

FIG. 2 is an enlarged cross-sectional view showing a step of forming a step absorption ceramic film 29, which is performed after a pre-press step of FIG.

FIG. 3 is a perspective view showing an appearance of a laminated chip coil 11 obtained by a manufacturing method described with reference to FIGS. 1 and 2;

FIG. 4 is a perspective view showing ceramic green sheets 15 to 18 prepared for obtaining the multilayer chip 12 shown in FIG. 3 separately from each other.

FIG. 5 is a perspective view showing a step absorbing ceramic film 29 separated from the ceramic green sheet 15 shown in FIG. 4;

FIG. 6 is an enlarged cross-sectional view illustrating a state where an internal conductor 2 is formed on a ceramic green sheet 1 for explaining a problem to be solved by the present invention.

FIG. 7 is a view for explaining a problem to be solved by the present invention, and shows a ceramic green sheet 1 shown in FIG. 6;
FIG. 4 is an enlarged cross-sectional view showing a step of forming a step absorption ceramic film 3 thereon.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Multilayer chip coil (multilayer ceramic electronic component) 12 Multilayer chip 15-18 Ceramic green sheet 19-21 Through hole 22-25 Internal conductor 28 Pressurized body 29-32 Ceramic film for step absorption 33 Raw ceramic material 34 Negative Pattern 35 screen

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ identification symbol FI // H05K 3/22 H05K 3/22 B 3/46 3/46 H (58) Fields surveyed (Int.Cl. ⁷ , DB (Name) H01F 41/04

Claims (4)

(57) [Claims] 1. A plurality of ceramic green sheets are prepared, an inner conductor is formed on a main surface of a specific one of the plurality of ceramic green sheets by a conductive paste, and the ceramic on which the inner conductor is formed is formed. A step including a raw ceramic material of substantially the same material system as the ceramic green sheet so as to absorb a step due to the thickness of the internal conductor in a region on the main surface of the green sheet where the internal conductor is not formed. Forming a ceramic film for absorption, and then stacking and pressing the plurality of ceramic green sheets, and a method for manufacturing a multilayer ceramic electronic component, the method further comprising: In order to flatten the conductor, the ceramic green sheet on which the inner conductor is formed is And further comprising a scan to process, the method of production of a multilayer ceramic electronic component. 2. In the step of forming the internal conductor,
The inner conductor has a width of less than 120 μm and a thickness of 20 μm
The method for manufacturing a multilayer ceramic electronic component according to claim 1, wherein the multilayer ceramic electronic component is formed on the ceramic green sheet with the above cross-sectional dimensions. 3. A specific ceramic green sheet is provided with a through hole, and the plurality of internal conductors are:
Formed to extend spirally through the through hole, applied to manufacture a laminated chip coil,
A method for manufacturing a multilayer ceramic electronic component according to claim 1. 4. The method for manufacturing a multilayer ceramic electronic component according to claim 1, wherein said step absorption ceramic film is formed by screen printing.